Gas burner



Jan. 19, 1932. BRANCHE 1,841,465

GAS BURNER Original Filed NOV. 15, 1928 INVENTDR Mason IBM/mm.

Kid.

ATTURNEY Patented Jan. 19, 1932 UNITED STTEI S PATENT orrlcr.

NELSON T. BRANCHE, OF TOLEDO, OHIO, ASSIGNOR TO SURFACE COMBUSTION CORPORA- TION, OF TOLEDO, OHIO, A CORPORATION OF NEW YORK ens nnnimn Application filed November 15, 1928, SeriaLNo. 319,704. .Renewed December 2, 1931.

This invention relates to improvements in A gas burners and more particularly to gas burners for use with heat-treating furnaces. The invention has among its objects to provide a gas burner which shall permit relatively great range of turndown of the mixture supply without back flash to the mixtureforming means. Another object is to provide a mixture-forming means of such construction that it may be positioned against the face of a furnace wall to discharge the mixture formed by it directly into a refractory tunnel formed or positioned in the furnace wall. Other objects will more fully appear hereinafter.

Referring to the drawing wherein the preferred embodiment of the invention is shown, the single figure thereof is an axial section through the improved burner and showing it as combined with a tunnel removably positioned in a furnace wall.

I11 the drawing, .10 indicates a metal head or plate having a depression 12 terminating in a short bore 14. Extending from the head is an open frame or bracket 16 having two axially spaced hubs 18 and 20. Supported by the hub 18 in axial alinement with the axis of the bore 14, is a relatively long mixing tube 22 one end of which terminates short of the bore 14. Alined with' -"said tube in front of its other end is a jet-orifice gas nozzle 24 which is secured in the end of a tubular fitting 26 which in turn is supoprted by the hub- 20. Fitting 26 is adapted for connec-- tion to a source of fuel gas under pressure.

The tube 22 has an entrance cone to pro mote the entry of primary air into the tube under the inducing action of the jet of gas discharged from the nozzle 24. The nozzle 24 is so proportioned and positioned with respect to the tube 22 that in normal operation the mixture of fuel gas and air discharged from the. tube 22 will be deficient in air for complete combustion.

7 However, the discharge end of the tube 22 is so located with respect to the bore 14 that additional air will be entrained into the mixture discharged from the tube.

In axial alinement with the bore 14 is a refractory tunnel 36 shown-as contained in a casing 38 which is secured to the head 10 whereby said tunnel and head together constitute a unit adapted for ready assemblage with a furnace wall 40. The tunnel is formed with two throats 32 and 34 of relatively different diameters. The throat 32 is preferably of uniform diameter throughout forms the entrance cone and the throat 34 the expansion cone or chamber.

The straight-run throat 32 of the tunnel 36 serves a two-fold purpose, namely, as a pas sage wherein the gas-rich mixture, when is suing from the preliminary mixing tube 22 with relatively high velocity and the secondary air which is entrained by said mixture, may thoroughly mix before entering the expanding chamber or throat 34 for burning therein; and as a combustion chamber proper where the gas-rich mixture may burn when the said mixture is issuing from the tube 22 with relatively low velocity. When the throat 32 is of somewhat greater diameter than that of the bore 14, as is preferred, the mixture leaving the bore 14 will immediately expand with consequent reduction of velocityand hence as long as the velocity of the mixture passing through the bore 14 is greater than'the rate of flame propagation in the mixture, back flash will not occur even though the mixture is burning in relatively close proximity to the discharge end of the bore 14.

Should the turndown be suflicient to allow the flame to cling to the discharge end of the tube 22, it may nevertheless be readily removed therefrom, without being extinguished by increasing the supply of the mixture, where upon the mixture will burn either in the throat 32 or in the throat 34 depending upon the velocity of the mixture as will now be readily understood. In normal operation, the mixture from the tube 22 will be in such volume and under such pressure that combustion will take place in the main combustion chamher or throat 34. At such times, the gas-rich mixture from the tube 22 and the secondary air entrained thereby will mix in passing througl'i the throat 32 as will now be readily understood. I

Adjustably mounted on the fitting 26 is a bell 28 the rim of which is adapted to seat against the head 10 when it is desired to cut off the entry of air into the furnace as when the burner is shut off, it being understood that a multiplicity of burners are usually provided and that it is sometimes desirable to shut ofi" one or more of the burners. The bell also serves as a means to regulate, within certain limits, the proportions of air and gas which enter the tunnel. Thus by restricting the free entry of air, the mixture can be made richer in gas than would ordinarily be the case; The bell alsoserves to materially reduce the noise of operation of the burner.

The tunnel is preferably formed by tamping refractory cement about a mandrel aligned with bore 14 as will be readily understood. A rim 42 on the outer wall of the depression 12 assists in holding the tunnel within the casing38.

Vhat is claimed is:

1. A gas burner comprising, in combination, an unobstructed refractory tunnel having a relatively long straight-run passage and a relatively long expansion chamber, an entrance cone to the straight run passage having a relatively short discharge bore of less diameter than that of said straight-run passage, and means projecting into said cone for directing a combustible gaseous mixture hrough said bore.

2. The combination with a furnace wall having a passage thcrethrough, oi a casing positioned in said passage, a head to which one end of said casing is secured, said head having'a dished portion extending into said casing, said portion having a central bore, said casing and head being removable from said passage as a unit, a combustion tunnel formed in said casing in axial alinement With said bore, a mixing tube projecting into said dished portion and adapted to discharge into said tunnel through said bore, a gas jet nozzle set to discharge into said tube, and means operable to close off said tunnel from the atmosphere.

3. In a gas burner, the combination of a refractory tunnel having a substantial portion of its length of substantially uniform diameter, means forming an entrance cone to said portion, a mixing tube for air and gas having its discharge end Within the confines of said cone, said tunnel having a step increase in diameter at the discharge end of said portion and gradually increasing in diameter from said step increase towards its discharge end.

4. In a gas burner, the combination of a jetorifice gas nozzle, a mixing tube Whereinto said nozzle discharges in a manner to entrain less than sufiicient air for complete combustion, a first throat whereinto said tube dis charges in a manner to entrain air, and a second throat of enlarged diameter Whereinto the first throat discharges. said throats forming a continuous tunnel, the first throat constituting a combustion chamber where the mixture burns when the velocity of the mix ture is less than is required to maintain combastion in the second throat and constituting a mixing'chambe'r when the velocity of the mixture suflicient to maintain combustion in the second throat.

5. In a gas burner, the combination of a jetorifice gas nozzle, a mixing tube whereinto said nozzle discharges in a manner to entrain less than sufficient air for complete combustion, a first throat whereinto said tube discharges in a manner to entrain air, and a sec- 0nd throat of enlarged diameter whereinto the first throat discharges, said throats forming a continuous tunnel, the first throat constituting a combustion chamber where the mixture burns when the velocity of the mixture is less than is required to maintain combustion in the second throat and constituting a mixing chamber when the velocity of the mixture is suflicient to maintain combustion in the second throat, said tube being of uniform internal diameter except for its entrance cone.

6. In a gas burner, the combination of a jetorifiee gas nozzle, a mixing tube whcreinto said nozzle discharges in a manner to entrain less than sulticient air For complete combustion, a first throat whereinto said tube discharges in a manner to entrain air, and a second throat of enlarged diameter \\-'hereinto the first throat discharges, said throats forming a continuous tunnel, the first throat constituting a combustion chamber, where the mixture burns when the velocity of the mixture is less than is required to maintain combustion in the second throat and constituting a mixing chamber when the velocity of the mixture is sufficient to maintain combustion in the second throat, said tube being of uniform inter nal diameter except for its entrance cone, the first throat being of substantially uniform diameter throughout its length.

7. In a gas burner, the combination of a jet orifice gas nozzle, a mixing tube whereinto said nozzle discharges in a manner to entrain v less than sufiicient air for complete combustion, a first throat whereinto said tube discharges in a manner to entrain air, and a second throat of enlarged diameter Whereinto the first throat discharges. said throats forming a continuous tunnel, the first throat constituting a combustion chamber where the mixture burns when the velocity of the mixture is less than is required to maintain'combustion in the second throat and constituting a mixing chamber when the velocity of. the mixture is sufficient to maintain combustion in the second throat, said tube being of uniform internal diameter except for its entrance cone, the second throat being longer than the first throat.

8. In a gas burner, the combination of a jetorifice gas nozzle, a mixing tube whereinto said nozzle discharges in a manner to entrain less than sulficient air for complete combustion, a first throat whereinto said tube discharges in a manner to entrain air, and a second throat of enlarged diameter whereinto the first throat discharges, said throats forming a continuous tunnel, the first throat constituting a combustion chamber where the mixture burns when the velocity of the mixture is less than is required to maintain combustion in the second throat and constituting a mixing chamber when the velocity of the mixture is suflicient to maintain combustion in the second throat, said tube being of uniform internal diameter except for its entrance cone, and means for controlling the admission of air into said tunnel.

9,. In a gas burner, the combination of a casing, a refractory tunnel within the casing, a head to which said casing is secured, an apertured portion in said head forming an entrance cone to said tunnel, a mixing tube discharglng into the tunnel'through said portion in a manner to entrain air, and a jet-orificegas nozzle discharging into said tube in a manner to entrain air.

10. In a gas burner, the combination of a casing, a refractory tunnel within the casing, a head to which said casing is secured, an

apertured portion in said head forming an entrance cone to said tunnel, a mixing tube discharging into the tunnel through said portion in a manner to entrain air, a jet-orifice gas nozzle discharging into said tube in a manner to entrain air and a bell forming a housing for said nozzle and tube.

In testimony whereof I aifix my signature.

NELSON T. BRANCHE. 

